Bio 111 Study Guide Chapter 13 Meiosis and Life Cycles

Transcription

1 Bio 111 Study Guide Chapter 13 Meiosis and Life Cycles BEFORE CLASS: Reading: Read the whole chapter from p Pay special attention to Figure 13.8, as it is such a good depiction of meiosis. Figure is a comparison of mitosis and meiosis. Don t let it confuse you; it may be really helpful to clarify some similarities and differences between the two processes. Definitions: gametes asexual reproduction sexual reproduction karyotype homologous chromosomes/homologs sex chromosomes autosomes diploid cell haploid cell fertilization zygote meiosis chiasmata synapsis crossing over

2 Questions/Problems: For questions 1-5, fill in the blanks with the words provided. Some words may be used more than once. asexual crossing over diploid fertilization gametes haploid sexual synapsis zygote 1. Meiosis begins with a (haploid/diploid) cell in the reproductive organs of an organism. It is the process that makes, which are (haploid/diploid) cells. 2. When homologous chromosomes pair up in Prophase I, this is called. Also, occurs between nonsister chromatids of the pairs when they exchange corresponding segments of DNA. 3. reproduction is when one parent produces offspring that are genetically identical to itself. 4. When two parents give rise to offspring that have genetic variation and unique combinations of genes, it is called reproduction. 5. The process of is when a sperm and egg unite. It results in the formation a (haploid/diploid) cell called a. 6. Recall learning in Chapter 12 how bacteria reproduce by simple cell division called binary fission. Sexual reproduction is far more complicated and difficult, and success is not guaranteed. After reading this chapter, what do you think is the main advantage of sexual reproduction? Why is it an advantage?

3 DURING CLASS: Types of Reproduction Basics Human Life Cycle Meiosis Purpose: Prophase I Metaphase I

4 Anaphase I Telophase I / Cytokinesis Prophase II Metaphase II Anaphase II Telophase II / Cytokinesis End Result

5 Bioflix Animation Meiosis Genetic Variability Independent assortment of chromosomes Crossing over Random fertilization Evolutionary Significance Compare and contrast mitosis and meiosis in a Venn diagram. **Take Away Concept** Meiosis is an amazing cellular process that, along with sexual reproduction, has the potential to give great evolutionary advantages to living organisms.

6 AFTER CLASS: Questions/Problems: 1. Label the following parts in the figure below: homologous chromosomes (homologs), sister chromatids, nonsister chromatids of a homologous pair, centromere, kinetochore, and chiasmata/crossing over. 2. Looking again at the above figure, in which phase of meiosis is the cell? 3. Meiosis II is similar to mitosis because a. sister chromatids separate. b. homologous chromosomes separate. c. DNA replication occurs during the division. d. they both take place in the same cells. e. haploid cells are almost always produced. 4. Which of the following is least likely to be a source of genetic variation in sexually reproducing organisms? a. crossing over b. replication of DNA during S phase before meiosis I c. independent assortment of chromosomes d. random fertilization of gametes e. All of the above contribute equally to genetic variation. 5. My cat Freckles has 38 chromosomes in his somatic cells. How many chromosomes did he inherit from each of his parents? How many chromosomes are in each of his gametes? If he sired kittens, how many chromosomes will be in each somatic cell of each of them?

7 6. Draw the chromosomes and other significant cell structures for a cell that is 2n = 4 as it goes through meiosis. Also, list any important information about each phase. Prophase I Metaphase I Anaphase I Telophase Prophase II Metaphase II Anaphase II Telophase II/Cytokinesis